An effervescent ice confection product is obtained by exposing CO.sub.2 - water clathrate-containing particles to such pressure, temperature and CO.sub.2 and water partial pressure conditions that a protective layer will be formed on the particles, mixing said particles with a liquid phase containing ice confection ingredients and usually solid ice and having a temperature such that frozen water will not melt therein and thereafter decreasing the temperature of the obtained mixture to a usual storage temperature.

(e) exposing the CO.sub.2 clathrate-ice composite particles to CO.sub.2, moisture, temperature and pressure conditions for a period of time sufficient to allow a protective coating to form on the surface of the clathrate particles which preventsloss of CO.sub.2 from the clathrate particles,

(f) mixing the partially frozen slurry and the coated clathrate particles; and

(g) further freezing the mixture to form a carbonated ice confection product.

2. Method according to claim 1 in which the partially frozen slurry contains water ice crystals in equilibrium with non-frozen fluid.

3. Method according to claim 1 in which prior to addition of the clathrate particles the partially frozen slurry is maintained at a temperature which is sufficient to maintain a partially frozen state.

4. Method according to claim 3 in which the partially frozen slurry is cooled to a temperature between 0.degree. and -7.degree. C.

5. Method according to claim 1 in which the solid CO.sub.2 clathrate-ice composition is formed in a pressurized reactor at a pressure of 35 bar.

6. Method according to claim 5 in which the CO.sub.2 clathrate-ice composition is formed by first contacting the CO.sub.2 with water at a temperature of 5.degree. C. and thereafter reducing the temperature to -15.degree. C. such that a solidCO.sub.2 ice clathrate forms.

7. Method according to claim 9 in which the CO.sub.2 clathrate-ice composition particles are between 200.mu. and 1 cm in size.

8. Method according to claim 7 in which the CO.sub.2 clathrate-ice composition particles are between 200 and 2000.mu. in size.

9. Method according to claim 8 in which the CO.sub.2 clathrate-ice composition particles are between 500 and 2000.mu. in size.

10. Method according to claim 7 in which the CO.sub.2 clathrate-ice composition particles are between 1 and 5 mm in size.

11. Method according to claim 7 in which the CO.sub.2 clathrate-ice composition particles are between 0.2 and 1 cm in size.

12. Method according to claim 1 in which the coated CO.sub.2 clathrate-ice composition particles are obtained by exposing the CO.sub.2 clathrate-ice composition particles to atmospheric conditions for at least 15 seconds to allow a protectivecoating of ice to form on the surface of the particles.

13. Method according to claim 12 in which the coated CO.sub.2 clathrate-ice composite particles are obtained by exposing the CO.sub.2 clathrate-ice particles to air for 30 seconds.

14. Method according to claim 1 in which the coated CO.sub.2 clathrate-ice composite particles are obtained by exposing the CO.sub.2 clathrate-ice composition particles to water vapor for a period of time sufficient to allow a protective coatingof ice to form on the surface of the particles.

15. Method according to claim 1 in which the mixture of partially frozen slurry and coated CO.sub.2 clathrate-ice composition particles is further frozen at -20.degree. C.

16. A carbonated ice confection product comprising a mixture of a flavored fluid phase which has been cooled to form a partially frozen slurry and ice coated CO.sub.2 clathrate-ice composition particles, wherein the ice coated CO.sub.2clathrate-ice composition particles have been formed by contacting CO.sub.2 with water under pressure at a cooling temperature such that a solid CO.sub.2 clathrate ice composite forms, grinding the solid composite to obtain CO.sub.2 clathrate-icecomposite particles and exposing the CO.sub.2 clathrate-ice composite particles to atmospheric conditions for a period of time to allow a protective ice coating to form on the surface of the clathrate particles which prevents loss of CO.sub.2 from suchcoated clathrate particles, and wherein the mixture is further frozen to form a carbonated ice confection product.

17. Ice confection product as in claim 16 in which the fluid phase comprises ingredients selected from the group consisting of liquid, sugar, flavoring, stabilizers, emulsifiers, protein, fat, air and mixtures thereof.

18. Ice confection product as in claim 16 in which the CO.sub.2 clathrate-ice composition particles are between 200.mu. and 1 cm in size.

19. Ice confection product as in claim 18 in which the CO.sub.2 clathrate-ice composition particles are between 200 and 2000.mu. in size.

20. Ice confection product as in claim 19 in which the CO.sub.2 clathrate-ice composition particles are between 500 and 2000.mu. in size.

21. Ice confection product as in claim 18 in which the CO.sub.2 clathrate-ice composition particles are between 1 and 5 mm in size.

22. Ice confection product as in claim 18 in which the CO.sub.2 clathrate-ice composition particles are between 0.2 and 1 cm in size.

Description:

In previous attempts to incorporate CO.sub.2 intoice confection products, the desired amount of CO.sub.2 could not be incorporated in a reproducible and controlled way to obtain the effervescing effect as known with carbonated drinks.

The invention now provides a method of preparing an ice confection product comprising combining particulate frozen water and a flavoured liquid phase and thereafter further cooling the obtained mixture, which is characterised in that CO.sub.2 -water clathrate-containing particles are exposed to such pressure, temperature and CO.sub.2 and water partial pressure conditions that a protective layer will be formed on the particle surfaces, and are mixed with the liquid phase which may contain solidice, the liquid phase having a temperature such that frozen water would not be melted or dissolved overall in said liquid phase and afterwards the temperature of the mixture is lowered to a usual storage temperature for ice confections. Usually theliquid phase comprises water-ice crystals before the clathrate-containing particles are added, which water-ice crystals are in equilibrium with the liquid phase and are forming therewith a slurry. This slurry may be obtained in a usual manner by feedingthe unfrozen mix to a scraped-surface heat exchanger wherein it is cooled to a temperature of about -0.degree. to -7.degree. C. or even lower.

In this specification CO.sub.2 - water clathrate is meant to comprise any CO.sub.2 -containing clathrate such as double clathrates and mixed clathrates. For a better description thereof reference is made to D. W. Davidson; Clathrate Hydrates inwater - A Comprehensive Treatise; Vol. 2, Chapter 3. Ed. Franks.

In practice it is to be preferred that the CO.sub.2 -water clathrate-containing particles are exposed to such CO.sub.2 pressure and temperature conditions, that CO.sub.2 will evolve from the particle surfaces until a protective ice layer isformed, which for practical purposes prevents further CO.sub.2 evolution under atmospheric conditions at temperatures below the melting temperature of ice. Usually this protective ice layer is formed within 15 seconds and consequently the stabilisationtreatment is to be carried out for more than 15 seconds.

A protective layer can also be formed around the CO.sub.2 -water clathrate-containing particles by exposing these particles to a water-containing environment under such conditions that a layer of solid water condenses on the surfaces of theparticles. This environment preferably comprises water vapour, which is condensed on the surfaces of the particles to form a solid protective ice layer thereon.

Although the particle sizes of the clathrate-containing particles can be of the same order as the ice particles in the ice confection product to which the clathrate is to be added, in practice preferably particle sizes of from 200 to 2000/.mu.areused. By incorporating relatively large clathrate-containing particles, preferably having sizes in the range 0.2 to 1 cm, a product is obtained giving a peculiar sensation on eating.

In this specification the term ice confection product is used in a broad sense, comprising products such as water-ice confection and ice-cream.

The invention will be exemplified in the following non-limiting examples.

EXAMPLE I

An ice mix containing

18 g sucrose

6 g corn syrup 63 DE (80% by weight)

0.1 g locust bean gum

0.3 g malic acid

0.25 g sodium citrate

0.45 g citric acid

3.0 g lemon concentrate

0.003 g tartrazine

0.15 g flavour (Zimmerman 139)

water to 100 g

is cooled in a scraped-wall heat exchanger to -5.degree. C. to form a fluid slush product.

In a pressurized reactor, CO.sub.2 is contacted with water at a pressure of 35 bar and a temperature of 5.degree. C. Thereafter the temperature is reduced to -15.degree. C., such that the carbonated composite solidifies. After removal from thereactor, the clathrate-ice composite formed by this procedure is ground in a cooled mill to a particle size of 500-2000/.mu.. These clathrate-ice composite particles are exposed to the atmosphere for 30 seconds and thereafter 25 g of this particulateclathrate-water ice composite is added to 75 g of the slush product as described above.

After mixing, the combined product is frozen to -20.degree. C. for storage.

EXAMPLE II

An ice mix containing

10% skim milk powder

2.6% whey powder

15% sucrose

7% dextrose monohydrate

2.5% maltodextrin DE 40

0.2% locust bean gum

0.02% kappa carrageenan

7% palm kernel oil

0.5% mgp (mono-diglyceride)

0.3% malic acid

0.3% sodium citrate

0.003% red colour (Ponceau 4R)

0.1% strawberry flavour (ex Bush Boake Allen)

water to 100%

is aerated and cooled in a scraped-surface heat exchanger to -6.degree. C. to form a creamy fluid.

A clathrate-containing product prepared as described in Example I is ground to coarse particles and a sieve fraction from 1 to 5 mm is separated, stabilized as described in Example I and admixed in an amount of 50 g to 250 g of creamy ice fluid. This combined mixture is frozen to -20.degree. C. for storage.